The invention relates to a protective tube for use in the sterilization of flexible endoscopes in vacuum.
The invention further relates to an endoscope having such a protective tube thereon.
The invention still further relates to a sterilization method for sterilizating an endoscope having such a protective tube thereon.
Flexible endoscopes differ from rigid endoscopes in that the shaft has a flexibility such that it can be bent, strongly curved or even have a loop-like form. When the flexible endoscope is configured for operations and diagnostic procedures, it is used particularly for the stomach and intestines. Such a flexible endoscope for operations is disclosed in the German patent publication DE 39 28 532.
A broader use of such flexible endoscopes is in veterinary medicine, where they are used to investigate the upper and lower respiratory tracts and the air cells in horses. These endoscopes can also be used to investigate ulcers in the stomach or intestine and the entire urogenital tract of horses and other animals. The length of the flexible shaft in such applications is up to 2 meters.
Flexible endoscopes for veterinary medicine are disclosed for example in the catalog xe2x80x9cEndoskopie in der Tiermedizinxe2x80x9d, 5th edition 1/95 from Karl Storz GmbH and Co., Tuttlingen, Germany. A xe2x80x98Universal Fiberskopxe2x80x99 with the article number 60309 VG is shown on page VET-H-FIB 3 in the catalog and comprises a headpiece from which a flexible shaft extends with a length of about 1 meter.
A distal end portion can be articulated even more extensively than the flexible shaft. This distal end portion can be bent or curved up to 220 degree with respect to the flexible shaft in a hook-like or semicircular arc-like manner. When the flexible shaft is inserted, for example past several turns in the intestinal tract, and then into a larger body cavity, for example the stomach, the distal end portion can be bent away from the longitudinal direction of the shaft by about 220 degrees in a circular arc and can also be rotated to the left or right by 90 degrees. In effect a complete panorama view of the region of the distal end is possible. To be able to perform these manipulations at the distal end portion of the shaft, it is provided with a particularly flexible sleeve which has the appearance of a rubber tube.
The covering of the flexible shaft in the remaining sections is relatively more rigid and has the appearance of a flexible plastic tube.
Thus the shaft on the whole is a flexible hollow pipe of tube-like form with several channels disposed in its interior, for example an instrument channel, several optical fiber channels, an image transmission channel with an objective at the end, a channel for cleaning and washing the objective and for example an insufflation channel. A rigid end piece is provided at the distal end face, which supports the distal ends of these various channels. The distal end portion with the particularly flexible rubber-like sleeve lies between this end piece and the longer flexible shaft.
A common technique for sterilization of such flexible endoscopes is to subject the endoscope to a vacuum in a closed space, where at the same time aggressive and microbiozidal media, for example hydrogen peroxide containing media, are employed as a sterilization agent.
In practice it has been found that the flexible sleeve at the distal end portion tends to swell and sometimes burst under vacuum. A pressure compensating cap is provided for venting the interior of the shaft during sterilization to allow pressure compensation between the interior of the shaft and the vacuum in the sterilization apparatus. The cap is provided on a special connector or at the head end, which is in communication with the interior of the shaft. Such a pressure compensating cap is shown on page VET-H-FIB 5 in the above-mentioned catalog with the article number 60025 E.
This pressure compensating cap comprises a valve through which air can escape from the interior of the shaft when a vacuum is applied to thereby provide pressure compensation. In practice it has been found that the aggressive sterilization agents can penetrate through the valve into the interior of the endoscope and can damage the components in the flexible shaft, in particular the sensitive optical equipment.
Instead of the compensating cap, other solutions have been attempted with a pressure compensating container. The amount of air drawn out of the interior of the endoscope when placed under vacuum is fed to the container and then flows back to the container when the vacuum is released. This however is very complicated in its construction.
The provision of a pressure compensating cap itself is complicated, but is necessary since otherwise the danger of leaks arise in the region of the distal end portion even after only a few sterilization cycles.
The object of the present invention is therefore to provide means which allow sterilization in the vacuum method and which ensure with constructively simple means that the flexible sleeve of the distal end portion is not damaged and no leaks arise.
According to the present invention, a protective tube is provided whose diameter is selected such that the tube fits to the distal end portion and can be slipped thereon. Its length is selected such that it at least covers the end portion having the flexible sleeve. The structure of the protective tube is such that the flexible sleeve is protected against swelling under vacuum conditions, where however the sterilizing agent can enter into the region between the outside of the sleeve and the mounted protective tube.
The protective tube is configured such that it acts as a type of support tube which protects the flexible sleeve of the distal end portion from inflating or swelling and therefore also against bursting. At the same time, its structure is partially open, i.e. is selected such that the sterilizing agent can reach between the protective tube and the outside of the sleeve, so that this region can also be thoroughly sterilized. The tube can be simply slipped onto the distal end portion before sterilization due to the selection of its corresponding diameter and also sits on the end portion so as not to fall off during corresponding handling procedures. By selecting the corresponding length, it is ensured that the entire length of the distal end portion, which is provided with such a flexible sleeve, does not swell and therefore burst when vacuum is applied.
Thus a protection of this critical region is provided against swelling, bursting and leakage with simple mechanical means. A further considerable advantage is that the interior of the endoscope or the shaft can be formed as a closed system against the sterilizing agent, such that no communication with the sterilizing environment exists, for example through valve openings or the like. It is thus excluded that the aggressive agents can enter into the interior. The selection of material for the protective tube to allow sufficient stability and to allow passage of the agents is easy to carry out and is adapted to the respective constructive features of the flexible endoscope.
In this manner, the object is completely achieved.
In an embodiment of the present invention, the structure of the protective tube is a fabric. This has the advantage that the textile or fabric configuration is very simple to fabricate and provides a stable but filigree netting with sufficient openings for passage of the sterilizing agent. The agent can reach the entire outer side of the sleeve of the distal end portion, over which the protective tube has been placed. In addition, such fabric structures are inexpensive to produce, so that such a protective tube can be formed as a one-use throwaway article.
In a further embodiment of the present invention, the protective tube comprises a flaring at at least one end. This feature has the advantage that the widened end helps to introduce the distal end portion into the protective tube or conversely to slide the protective tube onto the distal end portion of the flexible endoscope. Not only can the protective tube be slipped on in a simple manner, it is also guaranteed that the tube is not damaged and can be applied to be fully functional.
In a further embodiment of the present invention, the fabric is composed of fibers intertwined in spiral lines. The structure is similar to that of a reinforcing fabric, which is common in high pressure hoses, which is very simple to manufacture. On the other hand, a very reliable protection is provided against a swelling of the sleeve, even at low vacuums, so that even an inadvertent malfunction of the sterilizing chamber causing excessive vacuum is not harmful. Even in this case, the sleeve of the distal end portion is protected against being inflated or bursting.
The protective tube can be applied directly after manufacture and before the first sterilization procedure. It can remain on the end portion, which indicates to the user that this endoscope has been sterilized. This can also be performed for subsequent sterilization cycles, i.e. the protective tube can initially remain on the end portion after sterilization, so that an additional protection against mechanical disturbances is present and the protective tube is drawn off only just before use. The tube thus not only fulfills a function during the actual sterilization procedure, but also subsequently a protective function and at the same time an information function. The user is informed that the endoscope has actually been sterilized. Thus the invention also includes the combination of a flexible endoscope having a protective tube slipped onto its distal end portion.
A method for sterilizing a flexible endoscope under vacuum then comprises sliding a protective tube with the above-described features onto the distal end portion of an endoscope and performing sterilization under vacuum of the assembly comprising the endoscope and protective tube. Depending on the preference of the manufacturer or user, the protective tube can be removed immediately after sterilization or be pulled off just before use.
It will be understood that the above-mentioned features and those to be discussed below are not only applicable in the given combinations, but may also be used in other combinations or taken alone without departing from the scope of the present invention.